Some Gammaproteobacteria are enriched within CD14+ macrophages from intestinal lamina propria of Crohn's disease patients versus mucus

Abstract

Crohn's disease causes chronic inflammation in the gastrointestinal tract and its pathogenesis remains unclear. In the intestine of Crohn's disease patients, CD14⁺CD11⁺CD163^low macrophages contribute to inflammation through the induction of Th17 cells and production of inflammatory cytokines; the CD14⁺CD11c⁺163^high fraction is anti-inflammatory through the production of IL-10 in normal cases. In this report, the 16S rRNA gene amplicon sequencing method was used to identify bacteria that are specifically present in intestinal CD14⁺CD11c⁺ macrophages of Crohn's disease patients. Bacteria present in intestinal CD14⁺CD11c⁺ macrophages and mucus of Crohn's disease patients were separated into different clusters in principal coordinates analysis. There was a statistically significant increase in the relative composition of CD14⁺CD11c⁺ macrophages from mucus in two phyla (Proteobacteria [p = 0.01] and Actinobacteria [p = 0.02]) and two families (Moraxellaceae [p < 0.001] and Pseudomonadaceae [p = 0.01]). In addition, OTU-1: Acinetobacter and OTU-8: Pseudomonadaceae tended to concentrate in the CD14⁺CD11c⁺CD163^low subset, whereas OTU-10: Proteus, OTU-15: Collinsella tended to concentrate more in the CD14⁺CD11c⁺CD163^high subset than the other subset and mucus.